Time difference between MCE and a normal TV

Discussion in 'Windows Media Center' started by Cablecutter, Feb 3, 2005.

  1. Cablecutter

    Cablecutter Guest

    I have my MCE pc in a room next to the living room where my wife watches a
    tv-show. When tune in on the same show there is a time delay of a few
    seconds. How can I synchronise with a regular TV
     
    Cablecutter, Feb 3, 2005
    #1
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  2. There will always be a delay as Media Center is encoder and saving the video
    so you can pause and rewind.
     
    Michael Creasy [MSFT], Feb 3, 2005
    #2
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  3. Cablecutter

    Chris H. Guest

    Like Michael said, there is a built-in time delay. We have satellite feed
    for television, and the TV on the recorder box (DishNetwork) is behind the
    feed on the other TVs without the hard drive in the receivers, not to
    mention the recording feed on the MCE machines. It is the nature of the
    beast, so we can rewind if we've missed something.
    --
    Chris H.
    Microsoft Windows MVP/Tablet PC
    Tablet Creations - http://nicecreations.us/
    Associate Expert
    Expert Zone - www.microsoft.com/windowsxp/expertzone
     
    Chris H., Feb 3, 2005
    #3
  4. It doesn't need to be that way when you play from the 'live' point .
    So it was a design choice... maybe a valid one because I dont see the need for it myself
    and it would have complicated a bit development by having to source for the stream.

    Stephan
     
    Stephan Schaem, Feb 3, 2005
    #4
  5. Cablecutter

    Stephen Neal Guest

    Isn't the delay, at least with analogue TV, a partial result of the MPEG2
    encode and decode process requiring a long-ish number of frames in its
    buffer to do the motion analysis stuff to create the P and B frames between
    the MPEG I frames that exploit the temporal redundancy that gives MPEG2 good
    compression results.

    If you use a GOP of about 12 frames for encoding, you will introduce a 24
    frame or so delay in an encode and decode cycle - which is about a second?
    This is there even if you don't save to disk and replay from disk.

    MPEG2 introduces delays of its own if used in GOPs that aren't I frame only
    ? (In I-frame only mode it is pretty much the same as motion JPEG
    compression - each frame is encoded independently. However the compression
    introduced for a given picture quality is much lower...)

    Steve
     
    Stephen Neal, Feb 4, 2005
    #5
  6. You can't.

    MCE is always recording "live TV" to the hard drive, even if you are not
    "recording" the program, and when you watch "live TV", you are always
    watching a playback from the hard drive. There will always be at least
    a few seconds of delay.
     
    Barry Watzman, Feb 4, 2005
    #6
  7. Cablecutter

    JW Guest

    I agree with Stephen Neal.
    Yes, you are always playing from the "time shift buffer" which is on disk
    when watching Live TV however if the OS has not yet reused the memory space
    used to do write to the buffer it gets the data straight from Memory and
    since it tries to keep a couple of minutes of the buffer in memory you are
    not actually retrieving the data from disk. Even if you were the 8mb cache
    on the disk drive would give it back to you instantly.
     
    JW, Feb 4, 2005
    #7
  8. Cablecutter

    JW Guest

    Robert,
    I always enjoy your responses since your technical knowledge of the product
    far exceeds mine. It would help all of us sometimes if a member of the MS
    MCE staff would respond to some of these posts. For example it would be nice
    to know if they are considering the solution you propose of if not why not.
    Of course the staff could also publish articles in the Knowledge Base
    however they do not appear to use that as a communication medium to the
    world of MCE users.
    JW
     
    JW, Feb 4, 2005
    #8
  9. Sorry, but none of us can comment on future products or things we are
    considering.
     
    Michael Creasy [MSFT], Feb 4, 2005
    #9
  10. As Michael mentioned, Microsoft won't comment on any future features until
    a product is officially announced.

    You can rest assured, though, that they do follow these newsgroups, and
    that they do listen to my feedback as an MVP. Aside from that, the
    developers working for Microsoft would be the first to know exactly where
    the current product has its shortcomings, so they wouldn't really need
    anyone to tell them... But noone in the know would be allowed to publically
    disclose any future product plans.

    Regards,«
     
    Robert Schlabbach, Feb 4, 2005
    #10
  11. Cablecutter

    JW Guest

    I understand and support what you and Michael have stated relative to
    possible futures. However, is MS staff not allowed to state or publish in a
    Knowledge base article how and why something works without making any
    statement about the future or do they rely on MVPs such as yourself to pass
    along this information only when you feel it is required?
     
    JW, Feb 4, 2005
    #11
  12. Well, the Stream Buffer Engine itself is well documented here:

    http://msdn.microsoft.com/library/en-us/directshow/htm/usingthestreambuffer
    engine.asp

    As to a KB article, you mean one which confirms that MCE has a delay in
    live TV and that this delay is by design? Personally, I don't see much of
    value in a KB article which only confirms a shortcoming without offering
    any solutions, but I suppose some people might seek confirmation that their
    system is not misbehaving... Have you checked whether there possibly
    already is such an article...?

    Regards,«
     
    Robert Schlabbach, Feb 4, 2005
    #12
  13. Not at all; if you browse MSDN you'll find plenty of technical information
    regarding how components underlying Media Center work.
     
    Todd Bowra [MSFT], Feb 4, 2005
    #13
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